Characterization of the glycosylation profile of erythropoiesis-stimulating agents (ESAs) and impact on potency.

To evaluate the impact of glycosylation of Chinese Hamster Ovary (CHO) cell produced erythropoiesis-stimulating agents (ESAs) on in vivo efficacy, epoetin glycoforms were fractionated and characterized. A comprehensive series of biochemical, in vitro bio-functional analyses and in vivo potency assays were conducted to better understand the relationship of structure to function of epoetin glycoforms. The hyper-glycosylated ESA darbepoetin alfa was also assessed to understand the range of in vivo potency response. Results demonstrate a strong link between sialylation or antennary structure, but not between N-acetyllactosamine repeat number and in vivo potency. Results for darbepoetin as compared to epoetin also confirm an inverse relationship between in vivo potency and potency measured using in vitro methods.